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Biomedical subjects

D Appleton

Publications and source records attributed to D Appleton.

At least 19 recordsLinked to original sources
PubMed1992

Nutritional intake, height and weight of 11-12-year-old Northumbrian children in 1990 compared with information obtained in 1980.

There is little age-specific information on changes in dietary intake over time in this country, yet this is valuable in assessing the effectiveness of health education programmes particularly in vulnerable groups such as adolescents. In 1990, 379 children aged 12 years completed two 3 d dietary records. They were interviewed by one dietitian on the day after completion of each diary to verify and enlarge on the information provided and, with the aid of food models, obtain a quantitative record of food intake. Nutrient intake was calculated using computerized food tables. These children attended the same seven Middle schools in Northumberland as 405 children of the same age who recorded their diet using the same method, 10 years previously. Heights and weights were also recorded in both studies in the same manner. Comparing the nutrient intakes in 1990 with 1980, energy intake fell in the boys (to 8.6 MJ) but not in the girls (8.3 MJ). The contribution of fat to energy intake was unchanged at about 40% (about 90 g/d). Likewise, intake of sugars was unchanged at about 22% of energy (about 118 g/d). Calcium intake remained the same in the girls (763 mg/d in 1990) but fell in the boys (786 mg/d in 1990). Iron, vitamin C and unavailable carbohydrate intakes increased in both sexes, and the nutrient density of the diet improved in all sex and social-class groups. However, a social trend evident in 1980 still existed in 1990 with low social groups having the poorest-quality diet. It is concluded that there is little evidence of substantial progress towards improving the diet of adolescents in this country.

Body Height↗
PubMed1990

Particle spallation and plasticiser (DEHP) release from extracorporeal circuit tubing materials.

Particle spallation and plasticiser (DEHP) release from medical grade polyvinylchloride (PVC), co-extruded PVC-polyurethane (PIVIPOL)R and an experimentally produced co-extruded PVC-ethylene vinyl acetate (EVA) has been studied when used with manually occluded and self-occluding peristaltic pumps over a six hour pumping period. The shore hardness of the tubings studied were similar but the luminal coating thickness differed (0.2 mm polyurethane, 0.99 mm EVA). The pattern of particle release was similar for all materials on the pump type used with the majority of particles released being less than 5 microns in diameter. The number of particles greater than 5 microns released was independent of the tubing material but depended on the pump type. Particle release with self-occluding pumps was significantly higher (p less than 0.001) than for the manually occluded pump. Scanning electron microscopy indicated that the particles released originate from the repeated compression and flexing of the insert during pumping which leads to material structural failure. The higher release observed in the case of self-occluding pumps is suggestive of over-occlusion by the springs utilised in the pump. DEHP release (ppm) over a six hour period while perfused at 300 ml/min was significantly reduced for co-extruded tubing (0.56 +/- 0.05 mg (PVC-polyurethane) and 0.12 +/- 0.04 mg (PVC-EVA) compared with PVC (0.74 +/- 0.05 mg).

Diethylhexyl Phthalate↗
PubMed1986

Particle spallation induced by blood pumps in hemodialysis tubing sets.

The repeated flexion and compression of pump segments by the rollers of peristaltic pumps results in cracking and abrasion of the inner surfaces of the pump segment, leading to shedding of particles into the extracorporeal circuit. A series of studies to assess the rate of particle release from silicone rubber, polyvinyl chloride (PVC), and Pivipol, a coextruded polyurethane-coated PVC tubing, when these materials were used with blood pumps of the type found in hemodialysis units, was undertaken. The studies show that with all tubing/pump combinations there is an overall increase in the total number of particles released, but an analysis of the particle size distribution indicates that the majority of the particles are less than 16 micron in diameter. The rate of increase may be reduced, however, by decreasing the occlusion pressure.

Analysis of Variance↗
PubMed1984

Precision of digitized M-mode echocardiograms for clinical practice.

Computer digitization of M-Mode echocardiograms has proved a valuable research tool in the study of left ventricular function. It can be applied in clinical practice if the reproducibility of the technique is known so that imprecision can be minimised. Five normal echocardiograms of average clinical quality were selected and four cycles from each echocardiogram were digitized on two occasions by four different digitizers using an 'Apple II' computer. The study design allowed the sources of imprecision to be identified by analysis of variance. Assessment of the clinically most useful digitized measurement, peak rate of change of diastolic left ventricular dimension (dD/dt), was imprecise with a large within-subject variance and a 95% confidence interval of +/- 6.5 cm s-1; too wide for clinical use. The replication component accounted for 90% of this variance, with cycle to cycle and between-digitizer variance components being much less important. This large replication component will be reduced simply by repeating digitization; for dD/dt repeating digitization four times would theoretically reduce the confidence interval to a useful value of +/- 3.6 cm s-1. The 95% confidence interval for a single digitised measurement of diastolic left ventricular minor dimension was +/- 0.32 cm, for diastolic posterior wall thickness +/- 0.23 cm, and for the isovolumic relaxation time (A2-MVO) +/- 27 ms. Replication was again the largest component of variance so that the biggest improvement in precision will come from simply repeating digitization. Digitization on a cheap microcomputer system can provide clinically useful information provided reproducibility and sources of imprecision are known with clinical, as opposed to research, echocardiograms and conditions.

Adult↗
PubMed1982

Intensive attention improves glycaemic control in insulin-dependent diabetes without further advantage from home blood glucose monitoring: results of a controlled trial.

Forty-six diabetics treated with twice-daily insulin were seen every two weeks for six months in an intensive education programme aided by regular home urine glucose testing. Control was improved with a decrease in 24-hour urinary glucose excretion (median 138 mmol/24 h (24.8 g/24 h) falling to 70 mmol/24 h (12.6 g/24 h); p less than 0.002), glycosylated haemoglobin concentration (mean 11.4 +/- SD 2.3% falling to 10.4 +/- 1.5%; p less than 0.001), and Diastix score (median 3.0 falling to 1.3; p less than 0.001). There was no reported increase in hypoglycaemia. Thirty-eight of the diabetics proceeded to a nine-month randomised cross-over study of the effect on blood glucose control of monitoring urinary glucose or blood glucose measured visually or by a reflectance meter using appropriate reagent strips. No further improvement in control was observed after home blood glucose monitoring. Nevertheless, 29 out of 37 patients preferred blood to urine glucose monitoring. During both the education and cross-over studies there was evidence of an initial improvement in control followed by deterioration. This was independent of the monitoring method used in the cross-over period and may have been due to waning enthusiasm. Despite patient enthusiasm and other reports to the contrary, home blood glucose monitoring offered no improvement in control over intensive attention and conventional urine glucose monitoring.

Adolescent↗
PubMed1981

Natural history of autoimmune thyroiditis.

One hundred and sixty-three asymptomatic people with thyroid antibodies or raised serum thyrotrophin (TSH) concentrations, or both, and 209 age-matched and sex-matched controls without either marker of thyroid disorder were followed up for four years to determine the natural history of autoimmune thyroiditis. Mildly raised TSH concentrations alone and the presence of thyroid antibodies alone did not significantly increase the risk of developing overt hypothyroidism during the four years compared with the controls. Overt hypothyroidism developed at the rate of 5% a year in women who initially had both raised TSH concentrations and thyroid antibodies. Prophylactic treatment with thyroxine may be justified in women found to have both markers of impending thyroid failure. The cost effectiveness of screening the adult population remains to be evaluated.

Adult↗
PubMed1981

Disturbances of lactate metabolism in patients with liver damage due to paracetamol overdose.

Six patients with liver damage following paracetamol overdose, one patient with viral hepatitis and six control subjects were infused with sodium L(+) lactate. In controls the results were analysed using a single compartment model while in paracetamol patients a two compartment system was used to derive the fractional rate removal constant and lactate distribution volume. Forearm arterio-venous differences of lactate were also determined in order to assess the role of voluntary muscle in removal of a lactate load. In paracetamol patients with fractional rate removal constant was decreased to less than half the control value (P less than 0.001) while total distribution volume was similar to the two groups. Fasting lactate concentrations were significantly increased in paracetamol patients due to diminished lactate removal since the endogenous production rate of lactate was not significantly different from controls. A greater proportion of the lactate load was removed in voluntary muscle in paracetamol patients (39%) than controls (17%). Since the balance of lactate removal occurs principally in the liver, the decrease in the fractional rate removal constant in patients following paracetamol overdose indicates a severe derangement of hepatic lactate metabolism with a compensatory increase in lactate metabolism in voluntary muscle.

Acetaminophen↗
PubMed1978

Thyroid hormone concentrations in a large scale community survey. Effect of age, sex, illness and medication.

Total thyroid hormone concentrations have been measured in the course of a large scale community survey to determine the distribution of these variables in the normal population and to assess the effect of age, sex, previously undectected thyroid disease and medication upon these parameters. 2779 subjects were studied. Serum T4 concentrations were normally distributed. A progressive increase in T4 levels with age was noted in the males, and a smaller increase in females which was concealed by the raised T4 values secondary to oral contraceptive therapy in females under the age of 45. Serum T3 levels were also normally distributed. There was a small reduction in T3 with age in the males but this fall was not seen in the females. T3 values were relatively higher in females under the age of 45 but this increase was not noted after exclusion of subjects taking an oral contraceptive. The changes in thyroid hormone concentrations with age are relatively minor (particularly with respect to T3) in a randomly selected sample from an English town. It is suggested that the changes reported by other authors reflect the process of selection used, and the high frequency of undetected thyroid disease, other illness and medication in hospital-based communities.

Adolescent↗
PubMed1976

Assessment of thyroid hormone assays.

Four techniques for estimating serum T4 and three for estimating serum T3 have been investigated and found to be satisfactory in routine use. Normal ranges for each techniques have been established. Estimation of serum T3 by the commerical kits tested appears to have a high discriminant value in the diagnosis of hyperthyroidism, although the diagnostic definition used inevitably enhances the apparent sensitivity of these techniques. Estimation of serum T4 will identify the majority of patients with symptomatic hypothyroidism. The low sensitivity of T3 in the diagnosis of thyroid failure is confirmed.

Binding, Competitive↗